To provide a base isolation system capable of producing a base isolation effect, even if an earthquake occurs while a building and the foundation are connected and fixed for preventing the vibration due to wind.

A base isolation building equipped with a base isolation device 14 between the ground 30 and a building 16 comprises an anemometer 11 provided in the building 16 or in the vicinity of the building 16, a friction brake 20 stopping the movement of the building due to wind force and allowing the causing of displacement between the ground 30 and the building 16 when an earthquake exceeding a prescribed strength larger than wind force occurs during stoppage, and a control device 13 for controlling the friction brake so as to stop the movement of the building 16 when the wind velocity exceeds a prescribed value.